X-ray tube anode



Apr-i123, 1957 z, J ATLEE 2,790,102

X-RAY TUBE ANODE Filed Oct. 4, 1955 INVENTOR. z E D J. AT LE E fiMZw ATTOR NEYS United States Patent 2,790,102 X-RAY TUBE ANODE Zed J. Atlee, Chicago, Ill., assignor to Dunlee Corp., Chicago, 11]., a corporation of Illinois Application October 4, 1955, Serial No. 538,324

1 Claim. (Cl. 313-32) The present invention relates to X-ray tubes and more particularly to a new, improved X-ray tube anode.

During more or less continuous operation of an X- ray tube, the electrons impinging upon the anode generate considerable heat which must be dissipated to prevent overheating and destruction of the anode. In an effort to overcome the problem of overheating of the anode, various anode structures have been proposed and employed, including the use of a hollow copper anode body having "a cooling coil mounted therein, through which a coolant can be circulated to extract heat from the anode body. Such prior structures have exhibited several disadvantages. The cooling coil has generally been fixed to the anode body by means of a solder which presents a layer of relatively low heat conductivity so that the heat transfer from the body to the coolant has been inefiicient. Many of such proposed structures have had-thin wall sections in the copper anode body through which air could leak into the evacuated tube, destroying the necessary vacuum therein. A general disadvantage of such prior structures has been the high cost of manufacturing the same.

It is an object of the present invention to provide a new and improved X-ray tube anode having a coolant coil incorporated therein which overcomes the disadvantages mentioned above.

It is a specific object of the invention to provide an X-ray tube anode having a coolant coil incorporated therein in such fashion that heat may be transferred etficiently from the anode to the coolant fluid.

Another specific object is to provide an anode of the type described in which the wall sections are sufiiciently thick in 'all portions as to prevent leakage of air or other fluid therethrough.

Still another object is to provide an anode incorporating a coolant coil that may be manufactured at low cost.

Other objects and advantages of the invention will become more apparent hereinafter.

In accordance with the present invention, a coolant coil of gaseous impermeable metal is incorporated in an otherwise solid anode body of copper, as by casting the body about the coil so as to provide an inexpensively manufactured structure in which the coil and body are in intimate, efficient heat conducting contact.

For a more detailed description of the invention, reference is made to the accompanying drawings wherein:

Fig. 1 is a side elevational view of an X-ray tube embodying the invention;

Fig. 2 is a view of a longitudinal, medial section through the tube; and

Fig. 3 is an enlarged, sectional view through the anode taken substantially along line 3-3 of Fig. 2.

With reference to the views of the drawings, the X- ray tube of the invention is illustrated as comprising a cathode and an anode 12 mounted and sealed within an evacuated envelope 14. The envelope is illustrated as being formed of glass but the invention is not limited to any particular form, construction or configuration of the envelope, and it will be apparent that it may be formed of other material.

r'lhe cathode 10 may be constructed in any suitable manner and is illustrated as including an electron generating filament 20 mounted in a cup 21 formed in the end of the cathode facing the anode whereby the electrons generated by the filament are focussed upon the adjacent end of the anode.

The invention is not necessarily limited to any particular anode shape, style, or configuration and the anode 12 may comprise a generally cylindrical body 22 of suitable cast metal into which is set an X-ray generating target 24 of tungsten or other suitable material on the end thereof facing the cathode 10. The anode body 22 is formed with a shoulder 23 to which is secured, as by welding or brazing, one end of a mounting ring 26, the other end of the ring being sealed by a glass-to-metal seal, indicated at 28, to a re-entrant portion 30 of the envelope 14. A tubular skirt 34 may also be mounted at one end upon the anode body, with the skirt extending between the outer wall of the envelope 10 land the re-entrant portion 30, and supporting a getter ring 38 in a manner described and claimed in my prior Patent 2,502,070.

Because of the large amount of heat generated at the target 24, the anode body 22 is preferably formed of a metal or alloy of high heat conductivity, such as copper, so as rapidly to conduct the heat away from the target.

In accordance with the present invention, a portion of a tubular element is embedded in the body 22 so as to be in direct, intimate contact therewith whereby heat may transfer readily from the body to a coolant fluid circulated through the element. In the illustrated embodiment of the invention, the tubular element includes a flat, coiled portion 40 positioned in the body immediately adjacent the anode target 24. An inlet duct portion 44 leads to the coil and an outlet duct portion 46 leads from the coil portion, both the inlet and outlet ducts extending outwardly of the re-entrant portion of the envelope 14 for connection to a suitable coolant fluid circulating system. As indicated previously, the cooling coil may be incorporated in the body 22 by casting the body about the coil, though any other suitable process may be used.

Preferably, the tubular element or cooling coil is formed of a vacuum tight metal, such as molybdenum, so as to insure that the evacuated condition of the envelope 10 is not destroyed by leakage through the cooling coil and cast body 22 of the anode. Molybdenum has the further advantage that it is of higher melting point and insoluble in copper, therefore facilitating the casting of the anode.

It will be observed that the cooling coil and anode body 22 .are in intimate contact, facilitating transfer of heat from the copper anode body to the coil. Also, it will be noted that the anode body 22 is of relatively small diameter, whereby the length of the glass-to-metal seal 28 and the seal or joint between the anode body 22 and mounting ring 26 are relatively short, facilitating the initial manufacture of the tube and also minimizing the possibility of subsequent failure at some point along one of the seals.

Having illustrated and described a preferred embodiment of the invention, it should be apparent to those skilled in the art that the invention permits of modification in arrangement and detail. I claim as my invention all such modifications as come within the true spirit and scope of the appended claim.

I claim:

An X-ray tube comprising an evacuated envelope, an

anode comprisingacylindrical body of cast, cuprous maan inlet duct portion and an outlet duct portion extendterial extending within and without said envelope, means ingfrom saidicoil outwardlyof theiouter end, of said body. mounting said body in sealing relation to said envelope, an X-ray generating target mounted in the end of said References Cited inthe file Of this patent bodywithin said envelope, and means fonconduc'ting a 5 UNITED STATES PATENTS coolant fluid through said body-comprisingua tube of molybdenum cast in said body and including a coiled por- 2569872 Skehan 1951 tion positioned closely adjacent said body inner end and 

